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Dirty diesel also worse for the climate than petrol cars

Whilst EU regulations create an uneven playing field for diesel, fuel and vehicle taxes set at a member state level incentivise their purchase.

Two years after the Dieselgate scandal exposed the dirty nature of diesel cars, a new study by Transport & Environment (T&E) shows that diesel cars not only pollute the air but also emit more climate-change emissions (CO2) than petrol cars. A lifecycle analysis of vehicle emissions proves that over their lifetime diesel cars emit 3.65 tonnes of CO2 more than a petrol equivalent. Diesel’s higher climate impact is due to more energy being needed to refine diesel fuel; more materials required for the production of heavier and more complex engines; higher emissions from the biodiesel blended in the diesel fuel; and higher mileage because fuel is cheaper – see infographics below.

The study debunks carmakers’ claim that diesel cars are needed to meet their climate targets. A glance at carmakers’ marketing brochures and websites demonstrates that the difference between comparable diesel and petrol engines is negligible: from zero to a few grams of CO2. But diesel cars typically cost €2,000–3,000 more than petrol ones. Currently available alternatives such as petrol hybrid vehicles are priced similarly to diesel but emit around 20–25 per cent less CO2.

Julia Poliscanova, clean vehicles manager, said: “Dieselgate already exposed diesel cars to be the dominant cause of toxic nitrogen dioxide across European cities that is killing 68,000 Europeans annually. Contrary to industry claims, we have learned diesel cars are also worse for the climate than petrol versions and are not needed to meet car CO2 targets, Europe must now look forward and accelerate the transition to clean, electrified vehicles and consign dirty diesels to museums.”

In the EU, the car market is skewed in favour of diesels through biased regulations and unfair taxes. Whereas the diesel share in the EU is around 50 per cent, it is a niche product in the rest of the world. The EU buys 7 out of 10 diesel cars and vans sold globally, while less than one per cent of new vehicles sold in the US are diesel, and in China, the world’s largest vehicle market, diesel represents less than two per cent.

The study finds three causes for the EU’s addiction to diesel:

  1. Distorted national fuel and vehicle taxes. Diesel fuel is taxed between 10 and 40 per cent less than petrol in most countries. This “diesel bonus” cost national budgets almost €32 billion in lost tax revenue in 2016 alone.
  2. Unfair EU Euro emission standards that for decades allowed diesel cars to emit more NOx than petrol. This has been exacerbated by the use of obsolete tests (recently updated) and ineffective regulatory oversight that has allowed carmakers to fit cheap, ineffective exhaust controls that they turn down or off most of the time.
  3. Biased CO2 regulations that set weaker targets for carmakers that produce bigger and heavier diesel vehicles.

From an environmental perspective there is no justification to continue the preferential treatment diesel currently enjoys that has created the bloated EU diesel market, and now is the time to support and incentivise the shift to clean electric solutions. To create fair competition between technologies, EU policy needs to:

  • End biased vehicle emissions standards and propose a technology-neutral Euro 7 emission standard that would allow new diesel cars to emit no more NOx than state-of-the-art petrol cars;
  • Reform EU car CO2 regulations by getting rid of distortions in favour of heavier diesels, including accounting for vehicle km and introducing a zero-emission vehicles sales target to incentivise industry to increase the supply of electric vehicles and market them effectively;
  • Remove the diesel bonus and other biases in national tax regimes, and introduce fair fuel and vehicle taxes based on real-world CO2 emissions with an air quality increment.

Moreover, in response to the Dieselgate crisis, regulators must ensure there is a harmonised and effective approach to clean up 37 million dirty diesel cars and vans already on the road that is offered to all consumers EU-wide, and cities must put in place effective vehicle circulation restrictions when air pollution is above the recommended limits and ensure future low-emission zones are designed based on vehicles’ real-world performance.

Julia Poliscanova concluded: “The legacy of Dieselgate are the 37 million grossly polluting diesel cars still on Europe’s roads. While some of them will be taken off German roads, these dirty cars will soon end up in Central and Eastern Europe choking citizens there. We need concerted and coordinated action EU-wide to ensure these cars stop belching toxic fumes for another 10–15 years. It is time for the carmakers to take responsibility for their clean up and cash out for the local measures to tackle the urban air pollution crisis they have largely caused. National vehicle regulators must ensure this happens or the European Commission step in and sort out the mess.”

Source: T&E press release and study “Diesel – The true (dirty) story”, 18 September 2017. Link:

Lifecycle CO2 emissions from diesel and petrol cars.


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